Bacteria homolactic

The starter culture used in cheesemaking depends on the type of cheese and the temperature to which the curd is heated. Streptococcus lactis or S. cremoris are used in cheese varieties heated to 40°C or less, since no acid development occurs with these cultures above that temperature (Sellars and Babel 1970). High-temperature homolactic bacteria such as S. thermophilus, Lactobacillus bulgaricus, or L. helveticus are used in the manufacture of cheese varieties heated to higher temperatures. 

Metabolic engineering techniques have been applied to modify bacterial metabolism to direct it to the synthesis of compounds of interest. Ferain et al. [228] and Neves etal. [229] reported the production of mannitol hy Lb. plantarum and Lc. lactis (homolactic bacteria) strains when the lactate dehydrogenase gen was disrupted (Aldh). In these cases, mannitol was produced by reduction of... 

Fig. 1-4A. Embden-Meyerhof-Parnas (EMP) pathway for utilization of glucose by homolactic bacteria, (b) 6-Phosphogluconate (pentose phosphate) pathway for utilization of sugar by heterolactic bacteria.

Fig. 5.1. Metabolic pathway of glucose fermentation by homolactic bacteria...

Ingestion of commercial preparations that contain digestion-resistant starches and bacteria (e.g. homolactic lactobacilli) increases volatile fatty acid formation in the colon. This provides more fuel for colonocytes it is claimed regular intake of these preparations improves intestinal function and hence mood, known sometimes as die feel good factor. 

Acetic acid (Ca/Mg salt) Cheese whey, hemicelluloses, others Halophilic anaerobes Homolactic/homoacetic bacteria... 

In bacteria such situations are very common during fermentation. The end products of fermentation are continuously produced internally and excreted into the external medium (Fig. 11). The energy yield by efflux of fermentation products can be quite considerable. Recently, Michels et al. (30) calculated on theoretical grounds that the additional energy yield during homolactic fermentation is in the order of... 

Diacetyl may be synthesized by either homolactic or heterolactic pathways of sugar metabolism as well as by utilization of citric acid (Fig. 2.9). Citric acid is hrst converted to acetic acid and oxaloacetate the latter is then decarboxylated to pyruvate. Although earlier reports indicated that diacetyl synthesis by lactic acid bacteria does not proceed via a-acetolactate (Gottschalk, 1986), more recent evidence suggests that this pathway is active in lactic acid bacteria (Ramos et al., 1995). Here, pyruvate undergoes a second decarboxylation and condensation with thiamine pyrophosphate (TPP) to yield active acetaldehyde. This compound then reacts with another molecule of pyruvate to yield a-acetolactate, which, in... 

The industrial strains of lactic acid bacteria can completely ferment a medium of 12-15 % sugar in 2-4 days with greater than a 90 % yield of lactic acid. All of these bacteria are considered homofermentative in that they utilize a homolactic fermentation pathway, producing two molecules of lactic acid for each molecule of hexose. As diagrammed in O Fig. 1.10, the Embden-Meyerhof pathway is used in the homolactic fermentation. 

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